Capacitive divider device, voltage sensor, trip device module and electrical protection apparatus provided with such a device

Abstract

A multilayer capacitive divider having first and second main electrodes on the same level to apply an input voltage, and a common electrode on another level to supply an attenuated voltage, at least a first auxiliary electrode on yet another level, the electrodes arranged to form capacitive units, with the auxiliary electrode extending towards a side of the device towards which the second main electrode is arranged for connecting the auxiliary electrode to the second main electrode by a linear conductor. One such device also includes a voltage sensor, a trip device module and an electrical protection apparatus.

1. A capacitive divider device designed to attenuate an input voltage, said device comprising electrodes on different levels of a multilayer structure separated by insulating layers, said electrodes including a first and second main electrode to apply said input voltage, and a common electrode to supply an attenuated voltage from said input voltage, 
       wherein said first and second main electrodes are on the same level of said structure, the common electrode is on another level of said structure, said common electrode is arranged to form a first capacitive unit with the first main electrode and a second capacitive unit with the second main electrode, 
       wherein said device comprises at least a first auxiliary electrode on yet another level of the multilayer structure and arranged to form a first auxiliary capacitive unit with the common electrode, 
       and wherein said auxiliary electrode and the second main electrode extend towards one side of the multilayer structure to electrically connect said auxiliary electrode to the second main electrode via a linear conductor, said device additionally comprising a plurality of auxiliary electrodes on specific levels of the multilayer structure, each auxiliary electrode arranged to form an auxiliary capacitive unit with the auxiliary electrode on a consecutive specific level, said auxiliary electrodes connected either to the second main electrode or to the common electrode to obtain a parallel connection of each auxiliary capacitive unit with the second capacitive unit. 
     
     
       2. The device according to  claim 1 , comprising a predetermined number of auxiliary electrodes formed on specific levels of the multilayer structure presenting ranks going from 1 to N, the specific level of the first auxiliary electrode corresponding to rank 1, an auxiliary electrode arranged on a specific level of odd rank being connected to the second main electrode, an auxiliary electrode arranged on a specific level of even rank being connected to the common electrode. 
     
     
       3. The device according to  claim 2 , wherein each auxiliary electrode formed on a specific level of odd rank extends towards the side of the multilayer structure in which the second main electrode is arranged, each auxiliary electrode formed on a specific level of even rank and the common electrode extending towards a laterally opposite side so as to connect the electrodes to one another by means of linear conductors. 
     
     
       4. The device according to  claim 1 , wherein the specific levels of each auxiliary electrode correspond to consecutive levels of the multilayer structure. 
     
     
       5. A voltage sensor comprising:
 two input terminals of an input voltage, 
 a capacitive divider device connected to said input terminals to supply an attenuated voltage according to said input voltage, and 
 a processing circuit connected to said divider device to supply a signal representative of said input voltage, 
 
       wherein said capacitive divider device is designed to attenuate an input voltage, said device comprising electrodes on different levels of a multilayer structure separated by insulating layers, said electrodes including a first and second main electrode to apply said input voltage, and a common electrode to supply an attenuated voltage from said input voltage, 
       wherein said first and second main electrodes are on the same level of said structure, the common electrode is on another level of said structure, said common electrode is arranged to form a first capacitive unit with the first main electrode and a second capacitive unit with the second main electrode, 
       wherein said device comprises at least a first auxiliary electrode on yet another level of the multilayer structure and arranged to form a first auxiliary capacitive unit with the common electrode, 
       and wherein said auxiliary electrode and the second main electrode extend towards one side of the multilayer structure to electrically connect said auxiliary electrode to the second main electrode via a linear conductor, said input terminals being respectively connected to the first and second main electrode, and said processing circuit being connected to the common electrode. 
     
     
       6. The voltage sensor according to  claim 5 , wherein the processing circuit comprises impedance matching means. 
     
     
       7. The voltage sensor according to  claim 6 , wherein the impedance matching means comprise a resistor connected in parallel with the capacitive unit, the value of said resistor being chosen such as to minimize the cut-off frequency with respect to the operating frequency. 
     
     
       8. A trip device module for an electrical protection apparatus, said module comprising at least one current sensor to measure the current flowing in at least one electric conductor protected by said apparatus and processing means to supply a tripping signal according to the value of said current, 
       wherein said module comprises a voltage sensor according to  claim 5 , said processing means comprising means for determining a power and/or a power factor connected to said current sensor and to said voltage sensor, said tripping signal depending among other things on the value of said power and/or of said power factor. 
     
     
       9. An electrical protection apparatus designed to be installed on at least one electric conductor, said apparatus comprising a movable contact, an operating mechanism controlling opening or closing of said movable contact, and a trip device operating in conjunction with said mechanism to trigger opening of said movable contact in response to an electrical fault, wherein said trip device comprises a trip device module according to  claim 8 . 
     
     
       10. An electrical protection apparatus designed to be installed on at least one electric conductor, said apparatus comprising a movable contact, an operating mechanism controlling opening or closing of said movable contact, and a trip device operating in conjunction with said mechanism to trigger opening of said movable contact in response to an electrical fault, said trip device comprising a current sensor to measure the current flowing in said electric conductor and processing means to supply a tripping signal according to said current, 
       wherein the trip device further comprises a voltage sensor according to  claim 5 , said processing means comprising means for determining a power and/or a power factor connected to said current sensor and to said voltage sensor, said tripping signal depending on said value of the power and/or of said power factor.